Theodore Roosevelt Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Theodore Roosevelt Nature Center clear sky chart from 2005-11-06 to 2024-11-25.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	17% 7% 2 6% 4 4 4 4 5% 7% 40%	101449
	Night	18% 7% 2 6% 4 4 4 3 5% 6% 41%	98046
Transparency	Day	24% 47% 7% 13% 9% 1	104994
	Night	24% 46% 6% 13% 9% 1	102590
Seeing	Day	20% 14% 32% 22% 9% 2	15131
	Night	20% 13% 31% 27% 9% 1	24252

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	16% 6% 2 6% 3 4 3 3 4 5% 47%	2517
	11th to 20th	Day	16% 9% 2 6% 4 5% 5% 4 5% 6% 38%	2520
	21st to end	Day	22% 12% 4 7% 4 3 4 2 4 5% 32%	2968
February	1st to 10th	Day	17% 9% 2 6% 4 4 4 3 4 7% 39%	1762
	11th to 20th	Day	14% 7% 2 7% 5% 3 3 3 5% 6% 45%	1848
	21st to end	Day	20% 8% 3 7% 4 4 4 3 5% 5% 37%	1570
March	1st to 10th	Day	26% 8% 2 7% 3 3 3 3 4 5% 36%	3116
	11th to 20th	Day	9% 5% 2 5% 4 4 5% 5% 7% 9% 45%	3292
	21st to end	Day	20% 7% 2 6% 4 3 4 2 5% 5% 43%	4166
April	1st to 10th	Day	18% 8% 2 6% 4 4 4 3 5% 8% 38%	2280
	11th to 20th	Day	18% 6% 2 5% 4 4 4 3 5% 8% 41%	2254
	21st to end	Day	19% 6% 2 5% 4 3 4 4 6% 7% 39%	2327
May	1st to 10th	Day	27% 10% 2 5% 3 3 3 3 5% 8% 31%	4106
	11th to 20th	Day	26% 7% 2 6% 4 4 4 4 5% 7% 31%	4284
	21st to end	Day	15% 5% 2 5% 4 4 4 4 5% 9% 44%	4837
June	1st to 10th	Day	17% 6% 1 5% 4 4 4 4 6% 9% 38%	2660
	11th to 20th	Day	14% 7% 3 5% 4 5% 5% 4 6% 8% 39%	2660
	21st to end	Day	11% 5% 2 6% 5% 4 4 4 6% 9% 43%	2660
July	1st to 10th	Day	9% 7% 2 7% 6% 6% 6% 5% 7% 9% 36%	4440
	11th to 20th	Day	11% 7% 2 6% 4 5% 5% 5% 7% 10% 39%	4440
	21st to end	Day	14% 8% 3 7% 5% 5% 6% 5% 7% 9% 33%	4814
August	1st to 10th	Day	17% 7% 3 7% 4 5% 5% 5% 7% 9% 33%	4155
	11th to 20th	Day	12% 6% 2 6% 4 4 5% 4 7% 8% 41%	3730
	21st to end	Day	8% 5% 2 5% 3 4 5% 4 6% 10% 46%	4180
September	1st to 10th	Day	14% 5% 2 5% 4 5% 4 3 5% 8% 45%	2280
	11th to 20th	Day	11% 7% 2 4 3 3 4 4 4 8% 50%	2172
	21st to end	Day	19% 7% 3 6% 3 4 3 4 6% 5% 40%	2090
October	1st to 10th	Day	19% 6% 2 6% 4 4 4 3 4 7% 41%	2028
	11th to 20th	Day	15% 5% 2 4 5% 4 4 3 5% 6% 48%	1900
	21st to end	Day	19% 6% 2 6% 4 4 4 3 5% 7% 43%	1914
November	1st to 10th	Day	13% 6% 2 6% 3 3 3 3 4 5% 52%	1761
	11th to 20th	Day	16% 7% 3 4 2 3 3 3 4 6% 49%	1800
	21st to end	Day	15% 6% 2 5% 4 4 3 3 4 7% 45%	1720
December	1st to 10th	Day	18% 7% 2 6% 5% 3 3 4 5% 8% 38%	1520
	11th to 20th	Day	21% 7% 2 4 3 2 3 3 3 5% 45%	1906
	21st to end	Day	18% 10% 2 7% 5% 5% 4 5% 6% 6% 32%	2772
January	1st to 10th	Night	17% 7% 2 5% 3 3 3 2 4 6% 47%	4429
	11th to 20th	Night	17% 9% 3 6% 4 3 4 2 4 5% 44%	4440
	21st to end	Night	24% 11% 3 6% 4 3 4 3 4 5% 34%	4684
February	1st to 10th	Night	18% 8% 2 5% 4 4 3 3 5% 5% 42%	2417
	11th to 20th	Night	18% 8% 3 6% 5% 3 4 3 4 6% 41%	2218
	21st to end	Night	20% 7% 2 5% 4 4 3 3 4 5% 42%	1884
March	1st to 10th	Night	23% 12% 3 6% 3 3 3 3 3 5% 37%	3724
	11th to 20th	Night	12% 6% 2 7% 5% 4 5% 4 5% 6% 45%	3663
	21st to end	Night	21% 9% 2 6% 3 3 3 3 5% 4 41%	3466
April	1st to 10th	Night	19% 6% 3 7% 4 4 4 4 5% 6% 38%	1900
	11th to 20th	Night	19% 8% 3 5% 3 3 5% 3 6% 6% 40%	1875
	21st to end	Night	18% 8% 3 6% 4 4 4 3 4 6% 42%	1853
May	1st to 10th	Night	23% 11% 4 8% 4 3 3 3 5% 7% 28%	2834
	11th to 20th	Night	24% 9% 3 7% 5% 4 4 3 4 5% 32%	2637
	21st to end	Night	17% 8% 2 5% 4 3 4 3 5% 7% 41%	2738
June	1st to 10th	Night	17% 7% 2 4 5% 5% 4 3 5% 7% 40%	1520
	11th to 20th	Night	14% 8% 2 5% 4 4 4 5% 6% 9% 40%	1520
	21st to end	Night	10% 6% 2 7% 5% 4 6% 4 8% 9% 39%	1520
July	1st to 10th	Night	11% 8% 4 9% 6% 5% 5% 5% 6% 8% 33%	2520
	11th to 20th	Night	14% 6% 3 7% 5% 5% 5% 3 7% 9% 36%	2520
	21st to end	Night	17% 9% 3 7% 5% 4 4 4 6% 7% 34%	2739
August	1st to 10th	Night	23% 7% 3 6% 4 5% 4 4 6% 8% 31%	2741
	11th to 20th	Night	14% 6% 3 7% 5% 5% 5% 4 6% 8% 39%	3097
	21st to end	Night	8% 5% 2 5% 4 4 4 3 6% 8% 51%	3476
September	1st to 10th	Night	14% 6% 2 6% 4 5% 5% 4 6% 6% 44%	1900
	11th to 20th	Night	13% 5% 2 5% 4 3 3 3 5% 6% 52%	2006
	21st to end	Night	18% 6% 2 7% 5% 4 4 3 4 7% 41%	2090
October	1st to 10th	Night	20% 7% 2 7% 3 4 4 2 4 6% 42%	2150
	11th to 20th	Night	15% 5% 2 6% 3 3 4 3 4 6% 50%	2280
	21st to end	Night	21% 6% 2 6% 3 3 3 3 5% 5% 43%	2684
November	1st to 10th	Night	12% 5% 2 5% 4 4 4 3 4 6% 51%	2537
	11th to 20th	Night	19% 6% 2 5% 3 3 2 3 4 6% 49%	2600
	21st to end	Night	15% 5% 2 5% 5% 3 4 4 5% 6% 47%	2552
December	1st to 10th	Night	21% 7% 2 5% 4 4 4 3 5% 6% 39%	2660
	11th to 20th	Night	19% 7% 2 5% 3 4 4 3 5% 6% 43%	3288
	21st to end	Night	20% 9% 3 6% 4 4 4 3 5% 5% 38%	4884

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	25% 38% 4 21% 10% 2	2518
	11th to 20th	Day	30% 37% 6% 18% 8% 1	2520
	21st to end	Day	40% 39% 5% 11% 4 1	2968
February	1st to 10th	Day	17% 65% 6% 7% 3 1	1762
	11th to 20th	Day	15% 64% 2 10% 9% 1	1857
	21st to end	Day	17% 65% 5% 8% 4 1	1570
March	1st to 10th	Day	36% 41% 5% 11% 5% 1	3119
	11th to 20th	Day	18% 41% 8% 24% 8% 1	3292
	21st to end	Day	28% 40% 5% 9% 15% 4	4166
April	1st to 10th	Day	19% 65% 3 7% 5% 1	2280
	11th to 20th	Day	15% 66% 4 9% 7%	2254
	21st to end	Day	17% 65% 3 9% 6% 1	2327
May	1st to 10th	Day	36% 40% 12% 7% 5%	4120
	11th to 20th	Day	36% 41% 10% 11% 3	4288
	21st to end	Day	22% 40% 6% 18% 13% 1	4837
June	1st to 10th	Day	15% 65% 4 9% 7%	2660
	11th to 20th	Day	14% 65% 5% 9% 7%	2660
	21st to end	Day	13% 64% 5% 10% 8%	2660
July	1st to 10th	Day	29% 40% 8% 12% 11% 1	4370
	11th to 20th	Day	27% 38% 12% 14% 8% 1	4365
	21st to end	Day	33% 37% 8% 11% 9% 1	4661
August	1st to 10th	Day	32% 39% 10% 14% 5%	4141
	11th to 20th	Day	24% 39% 8% 24% 4	3766
	21st to end	Day	17% 39% 8% 21% 14% 1	4180
September	1st to 10th	Day	15% 60% 7% 10% 7% 1	2280
	11th to 20th	Day	15% 61% 3 9% 11%	2172
	21st to end	Day	22% 60% 4 8% 6%	2090
October	1st to 10th	Day	20% 40% 7% 10% 18% 5%	3366
	11th to 20th	Day	11% 37% 6% 14% 26% 4	3140
	21st to end	Day	13% 37% 11% 18% 19% 2	3126
November	1st to 10th	Day	18% 55% 7% 9% 10% 1	1761
	11th to 20th	Day	14% 56% 3 12% 14% 2	1800
	21st to end	Day	15% 58% 6% 14% 5% 2	1720
December	1st to 10th	Day	21% 59% 6% 6% 7%	1520
	11th to 20th	Day	22% 48% 6% 12% 11% 1	1906
	21st to end	Day	36% 37% 5% 16% 5%	2772
January	1st to 10th	Night	26% 36% 6% 22% 7% 3	4429
	11th to 20th	Night	27% 36% 8% 17% 10% 2	4440
	21st to end	Night	40% 39% 3 12% 5% 1	4684
February	1st to 10th	Night	16% 64% 6% 10% 3 1	2417
	11th to 20th	Night	16% 63% 2 7% 9% 2	2220
	21st to end	Night	17% 64% 4 7% 6% 2	1884
March	1st to 10th	Night	38% 40% 4 11% 5% 1	3734
	11th to 20th	Night	21% 41% 8% 18% 11% 2	3664
	21st to end	Night	30% 40% 3 7% 15% 4	3466
April	1st to 10th	Night	18% 64% 3 8% 6% 1	1900
	11th to 20th	Night	13% 66% 5% 9% 7%	1875
	21st to end	Night	17% 65% 3 8% 6% 1	1853
May	1st to 10th	Night	37% 40% 8% 10% 4	2840
	11th to 20th	Night	38% 40% 11% 9% 3	2638
	21st to end	Night	27% 40% 7% 16% 9% 1	2739
June	1st to 10th	Night	16% 64% 2 9% 9%	1520
	11th to 20th	Night	14% 66% 4 11% 5%	1520
	21st to end	Night	13% 65% 4 10% 7% 1	1520
July	1st to 10th	Night	32% 40% 8% 12% 8%	2480
	11th to 20th	Night	30% 37% 10% 16% 6%	2472
	21st to end	Night	34% 36% 10% 8% 11% 1	2651
August	1st to 10th	Night	38% 38% 11% 9% 4	2731
	11th to 20th	Night	27% 39% 9% 19% 5%	3127
	21st to end	Night	16% 38% 7% 26% 13%	3476
September	1st to 10th	Night	15% 60% 5% 12% 7% 1	1900
	11th to 20th	Night	15% 60% 4 9% 10% 2	2006
	21st to end	Night	22% 60% 3 8% 6% 1	2090
October	1st to 10th	Night	24% 37% 7% 15% 14% 2	3592
	11th to 20th	Night	9% 37% 5% 19% 27% 3	3779
	21st to end	Night	15% 36% 8% 22% 16% 2	4422
November	1st to 10th	Night	17% 56% 5% 11% 9% 2	2537
	11th to 20th	Night	16% 56% 3 10% 12% 3	2600
	21st to end	Night	15% 58% 6% 13% 6% 1	2552
December	1st to 10th	Night	21% 60% 5% 9% 5%	2660
	11th to 20th	Night	22% 48% 5% 10% 12% 2	3288
	21st to end	Night	33% 37% 6% 16% 7%	4884

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	26% 23% 33% 16% 3	180
	11th to 20th	Day	24% 27% 31% 15% 3	180
	21st to end	Day	21% 22% 39% 13% 5% 1	254
February	1st to 10th	Day	27% 20% 37% 14% 2	322
	11th to 20th	Day	24% 21% 41% 13% 2	456
	21st to end	Day	28% 20% 34% 14% 4	382
March	1st to 10th	Day	23% 22% 33% 18% 3	460
	11th to 20th	Day	21% 22% 36% 16% 4 1	460
	21st to end	Day	30% 18% 32% 14% 5% 1	506
April	1st to 10th	Day	27% 21% 32% 14% 6% 1	460
	11th to 20th	Day	25% 18% 32% 17% 6% 1	452
	21st to end	Day	29% 18% 33% 16% 4 1	460
May	1st to 10th	Day	29% 19% 30% 17% 5% 1	463
	11th to 20th	Day	21% 15% 36% 21% 6% 1	487
	21st to end	Day	17% 9% 32% 26% 13% 2	529
June	1st to 10th	Day	18% 11% 32% 28% 10% 2	490
	11th to 20th	Day	15% 11% 35% 28% 9% 2	490
	21st to end	Day	13% 9% 35% 28% 12% 2	490
July	1st to 10th	Day	12% 9% 26% 34% 14% 5%	485
	11th to 20th	Day	10% 5% 30% 35% 16% 4	484
	21st to end	Day	14% 10% 31% 29% 14% 3	532
August	1st to 10th	Day	14% 7% 27% 32% 15% 5%	486
	11th to 20th	Day	15% 5% 26% 35% 15% 4	479
	21st to end	Day	12% 7% 30% 31% 14% 6%	539
September	1st to 10th	Day	19% 7% 29% 25% 16% 4	490
	11th to 20th	Day	14% 7% 30% 24% 15% 10%	490
	21st to end	Day	23% 9% 29% 22% 12% 4	490
October	1st to 10th	Day	24% 10% 26% 22% 14% 5%	490
	11th to 20th	Day	17% 15% 32% 22% 12% 2	490
	21st to end	Day	21% 13% 36% 19% 9% 2	446
November	1st to 10th	Day	15% 15% 32% 26% 9% 2	395
	11th to 20th	Day	22% 23% 30% 19% 6% 1	400
	21st to end	Day	20% 19% 30% 23% 7% 1	356
December	1st to 10th	Day	23% 23% 34% 15% 5% 1	180
	11th to 20th	Day	32% 21% 33% 10% 3	180
	21st to end	Day	26% 18% 36% 14% 6% 1	198
January	1st to 10th	Night	20% 20% 38% 20% 3	760
	11th to 20th	Night	24% 19% 30% 23% 3	760
	21st to end	Night	19% 19% 38% 21% 2	836
February	1st to 10th	Night	21% 18% 36% 23% 2	760
	11th to 20th	Night	23% 21% 38% 16% 2	743
	21st to end	Night	24% 20% 35% 17% 4	628
March	1st to 10th	Night	24% 18% 34% 19% 5%	760
	11th to 20th	Night	21% 18% 38% 19% 4 1	760
	21st to end	Night	23% 17% 36% 20% 4	836
April	1st to 10th	Night	24% 18% 34% 20% 5%	760
	11th to 20th	Night	22% 14% 35% 24% 5%	751
	21st to end	Night	22% 15% 33% 25% 5% 1	713
May	1st to 10th	Night	24% 11% 33% 24% 7% 1	570
	11th to 20th	Night	23% 13% 33% 27% 4	464
	21st to end	Night	21% 5% 23% 37% 13% 1	411
June	1st to 10th	Night	20% 7% 27% 33% 13% 1	380
	11th to 20th	Night	14% 7% 24% 40% 14% 1	380
	21st to end	Night	11% 6% 27% 45% 10% 1	380
July	1st to 10th	Night	12% 4 24% 44% 15% 1	370
	11th to 20th	Night	14% 4 23% 42% 15% 2	368
	21st to end	Night	13% 6% 23% 42% 16%	416
August	1st to 10th	Night	11% 3 27% 42% 17% 1	509
	11th to 20th	Night	15% 4 20% 36% 22% 2	750
	21st to end	Night	14% 4 19% 38% 22% 3	836
September	1st to 10th	Night	16% 5% 26% 34% 17% 3	760
	11th to 20th	Night	15% 5% 22% 33% 19% 6%	760
	21st to end	Night	21% 5% 26% 29% 16% 2	760
October	1st to 10th	Night	23% 9% 24% 27% 15% 3	760
	11th to 20th	Night	17% 13% 29% 29% 12% 1	760
	21st to end	Night	24% 12% 32% 24% 8%	836
November	1st to 10th	Night	15% 13% 34% 27% 11% 2	780
	11th to 20th	Night	22% 15% 34% 22% 7%	800
	21st to end	Night	18% 17% 32% 25% 7% 1	779
December	1st to 10th	Night	26% 17% 33% 19% 5% 1	760
	11th to 20th	Night	23% 17% 35% 22% 4	760
	21st to end	Night	23% 16% 37% 22% 3	836

Page generated at 2024-11-22 08:02:27. Version ac07

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